This is a graduate training program designed to provide research training experience in Investigative Gastroenterology and in cell and molecular biology and physiology of the digestive tract for: 1) physicians who have completed their clinical training in Gastroenterology (either in the Department of Internal Medicine or in the Department of Pediatrics) to enable these physician-scientists to establish careers for the independent investigation of the digestive tract and 2) Ph.D. scientists who are seeking post-doctoral training in the cell biology and physiology of the digestive tract. This training program will combine the resources of the Gastroenterology Unit of the Department of Internal Medicine and the Departments of Cell Biology and Cellular and Molecular Physiology and will emphasize active participation in laboratory research in the physiology, pathophysiology and cell and molecular biology of the digestive tract with particular emphasis on epithelial cells. Some physician-trainees may enroll in the recently established Ph.D. granting Investigative Medicine Program. Attendance at lectures and research seminars will also be encouraged. Post-doctoral trainees will be either physicians who completed their clinical training in Gastroenterology who will receive three (or more) years of research training or Ph.D's with an interest in the physiology and cell biology of the digestive tract who will receive two years of research training. Heavy emphasis in the selection process will be given to those individuals desiring research training experience as preparation for the start of a career in Academic Medicine. We anticipate no more than four post-doctoral trainees at any one time. The primary training facility will be the research laboratories of the Gastroenterology Unit of the Department of Internal Medicine and the research laboratories of the Departments of Cell Biology & Cell and Molecular Physiology at Yale University School of Medicine.